Process and apparatus for drying caking products



Nov. 12, 1957 M. K'LING 2,812,591

PROCESS AND APPARATUS FOR DRYING CAKING PRODUCTS Filed Feb. 25, 1955 3Sheets-Sheet 1 F l G. I.

m /2 \f\\\\\\ g IXIVENTOR MAURICE KLING ATTORNEYS M. KLING 2,812,591PROCESS AND APPARATUS FOR DRYING CAKING PRODUCTS Nov, 12, 1957 5Sheets-Sheet 2 Filed Feb. 25 1955 MAURICE INVENIOR KLI N 6 Nov. 12, 1957u c; 2,812,591

PROCESS AND APPARATUS FOR DRYING CAKING PRODUCTS Filed Feb. 25, 1955 5Sheets-Sheet 5 FIG. 3.

INVENTOR MAURICE KLING BY Mrza ATTORNEYp United States Patent PROCESSAND APPARATUS FOR DRYING CAKING PRODUCTS Maurice Kling, Fontainebleau,France, assignor t Societe Anonyme Preparation Industrielle desCombustlbles, Fontainebleau, France Application February 25, 1955,Serial No. 490,632

Claims priority, application France March 5, 1954 8 Claims. (CI. 34-12)This invention relates to processes and apparatus for drying productsand has more particular reference to processes and apparatus for dryingcalring products such as mud or products of colloidal or semi-colloidalstructure.

Drying of caking products such as mud or products of colloidal orsemi-colloidal structure presents difficulties caused by the fact thatrational and homogeneous drying of a product calls for a very finedivision of the particles in order to obtain an intimate contact betweenthe particles and the drying medium. This division is diflicult toobtain with muddy and caking products. In fact, these products tend toform lumps which only dry superficially and whose core remainsinaccessible to heat exchange, owing to the defective heat transmissionfrequent in these products, especially when they are clayey.

Known are driers which employ two cylinders for crushing the lumps ofsuch products; however, these driers feed directly a pair of dryingcylinders andthe products, which only remain in contact with thesecylinders for a very short period, finish drying in falling upon otherheat exchange elements, causing the destruction of the layer obtained bythe passage between the two cylinders, so that products insufficientlydried when leaving the cylinders are likely to re-agglomerate.

The object of the present invention is to provide a novel process of andimproved apparatus for overcoming the above defects by presenting theproducts to be dried in the form of a very thin endless layer, placedupon a moving surface on which they remain, .and which carries themforward during the drying process, in order to leave them intact and tobring them into contact with a series of laminating cylinders.

Another object of the present invention is to provideimproved apparatus,as characterized above, wherein the moving surface which receives thethin endless layer of the products to be dried comprises a largecylinder mounted in a chamber and wherein the products to be treated arefed between a spaced pair of feed cylinders to form the thin endlesslayer which is placed upon the large cylinder.

A further object of the present invention is to provide improvedapparatus, as characterized above, wherein said large cylinder ismounted for rotation about a fixed axis and said other cylinders aremounted for rotation about an axis movable toward and from the largecylinder so that these cylinders may move outward to permit the passageof any foreign objects in the products being treated.

Other objects and advantages of the invention will appear in thefollowing specification when considered with the accompanying drawings,wherein:

Fig. 1 is a diagrammatic side elevational view show ing one embodimentof a drier construction in accordance with the present invention;

Fig. 2 is a view similar to that shown in Fig. 1, but showing a modifiedform of apparatus-and Fig. 3 is a view similar to that shown in Fig. 1,but

' rotatably mounted therein.

ice

showing still another modified form of the apparatus.

The present invention provides a novel process and improved apparatusfor drying caking products such 'asmud or the like and, in general,comprises a drying chamber in which is mounted a movable surface in theform of a large cylinder; a pair of feed cylinders positioned to receivebetween them the lump products to be treated and crush and press theminto a very thin endless layer which moves onto the large cylinderandrotates therewith while being pressed by a plurality of laminatingcylinders. A flow of heated drying gas continuously flows through thechamber for heating the cylinders and the product. The flow of thedrying gas through the chamber ma be either methodic or antim'ethodic.

After the thin layer of products has passed between the last of thelaminating cylinders and the large cylinder, it will be completely driedand. break up and fall into the outlet chute from the chamber.

The invention further contemplates mounting the cylinders between whichthe layer of products passes, movable relative to one another so thatforeign bodies in the products may readily pass through the apparatus.

Referring now to the drawings, there is diagrammatically illustrated inFig. 1, one embodiment of a drier constructed in accordance with thepresent invention. As there shown, the drier comprises an elongatedsubstantialy rectangular chamber 16 having an inlet opening 11 for thehot drying gases and an outlet opening 12 for the exhausting of thedrying gases; a feed. plate 13 through which the products to be driedare fed into a feed chute 14 opening into the chamber; a large hollowcentral cylinder 15 rotatably mounted therein; a. pair of feed cylinders16 and 17 rotatably mounted therein; a scraper 18; and a plurality oflaminating cylinders 19 and 20 The cylinders 16, 17, 19 and 20,preferably and as shown, are hollow.

The operation of the apparatus is as follows:

The products to be treated are fed through the feed plate 13 with aconstant or intermittent output and are discharged through the chute 14between the feed cylinders 16 and 17, which rotate in oppositedirections, as indicated by the arrows, and which crush the lumps andelongate them into a layer adhering to the cylinder 17. The productsremaining caked upon the cylinder 16 are scraped oif by the scrapingblade 18 and fall upon the cylinder 15, which, as it rotates, bringsthem into contact with cylinder 17, so that all the products fallingbetween the feed cylinders 16 and 17 are formed into a thin solid layercalipered by the distance between the two feed cylinders. The thinendless layer of products formed by the passage of the products betweenthe two feed cylinders passes downwardly onto the large central cylinder15 and is carried along by this cylinder as it rotates and issuccessively brought into contact with the laminating cylinders 19 and20 rotating inversely to the large cylinder at a predetermined speed,which may be the same as or different from the peripheric speed of thelarge cylinder. These laminating cylinders compress the layer more andmore, as a series of rolling mills, whileleaving the upper surface ofthe layer between the cylinders 17, 19 and 20 in free contact with thehot gases. The hollow cylinders have both their external and internalsurfaces heated by the hot gases and transmit this heat direct to theproducts being dried. After passing between the large cylinder and. thelowermost of the laminating cylinders, the dried layer breaks up andfalls through .the chamber and passes out through the opening 11. As theproducts fall through the chamber they will be further dried by directcontact with the hot gases.

This method, while giving excellent exchange conditions between theheating gases and the products to be dried, is dangerous when theseproducts are of an in flammable nature.

The modified form of drying apparatus diagrammatically illustrated inFig. 2, provides for an anti-methodic circulation of the drying gas. Inthis modification, the chamber the feed plate 13', chute 14', scraper1.8, and cylinders 15, 16', 17', 19 and 20' are generally similar to thecorresponding members as shown in Fig. 1. However, in this particularmodification, the hot drying gases enter the chamber 10' through opening12, pass over the several cylinders, and are drawn into an expandingchamber 21 located on the discharge side of the dried products, by meansof a blower 22 which draws the gases, containing small products, fromthe expansion chamber 21 through a conduit 23 and discharges themthrough pipe 24 into the feed chute 14 of the feeder 13. The gases arethen discharged on one or both sides of the chute 14. Thus is obtainedthe precipitation of the small particles in suspension in the dryinggases by this rough projection on a surface wetted by the moist productsentering the drier or on the moist products themselves. The driedproducts are evacuated through opening 11. a

In Fig. 3 there is diagrammatically illustrated another modification ofdrying apparatus constructed in accordance with the present invention.In this particular modification, the chamber 10 with its expansionchamber 21 feeder 13 with its chute 14", scraper l8", blower 22' withits suction and discharge pipe lines 23 and 24, respectively, aregenerally similar to the corresponding parts shown in Fig. 2. Also, thecylinders 15", 16", 17", 19" and 20", except for the manner in whichthey are mounted, are generally similar to the corresponding membersshown in Fig. 2.

As shown in Fig. 3, the cylinder 15" rotates between fixed bearings 25suitably mounted on a structural frame indicated generally at 26,formed, in the chamber 1%. Cylinder 16 rotates between movable bearings27 slidably mounted between two vertically spaced, horizontallyextending parallel slid-es 28, suitably mounted in the structural frame26. Each of the bearings 27 is pressed against adjustable thrust members29 by suitable compression springs 30. Screws 31 and 32 adjust thethrust members and springs respectively.

Cylinders 17", 19 and 20 rotate in bearings 33, 34 and 35, respectively.The bearings 33 are slidably mounted in vertical parallel slide guides36 secured on the frame structure 26 and are resiliently pressed againstadjustable thrusts 37 by adjustable springs 38. Thrusts 37 areadjustable, as by means of screws 39, and springs 38 are regulated as byscrews 40. Bearings 34 are mounted at the end of a pair of levers 41which are hinged upon the bearings 33; bearings are mounted at the endof a pair of levers 42 which are hinged on bearings 34. Bearings 34 arepushed by adjustable springs 43 onto adjustable thrusts 44. Bearings 35are pushed by adjustable springs onto adjustable thrusts 46. Theforegoing construction provides a movable suspension of the compressingcylinders while an adjustable and accurate position of these cylindersis assured in relation to cylinder 15", with the help of the thrusts 37,44 and 46. The springs 38, 43 and 45 permit the cylinders to move awayfrom the cylinder 15" to permit foreign objects in the products to passtherebetween.

The drive of the cylinder assembly is provided as by a chain 47 drivenby a pinion 48 and driving pinions d9, 50 and 51 keyed to the shafts ofcylinders 15', 16 and 17", respectively. The pinion 48 is driven by anysuitable means, not shown, and the chain 47 is properly tensioned as bya tensioning pinion 52. Cylinder 19" is driven by cylinder 17" as bymeans of a driving chain belt 53 passing over pinions keyed on theshafts of cylinders 17" and 19", respectively. Cylinder 2t) is driven bycylinder 19" as by means of a drive chain belt 54 passing over pinionskeyed on the shafts of cylinders 19" and 20", respectively.

The operation of this modification of drying apparatus is identical tothat shown in Fig. 2, except that all of the small cylinders are mountedfor movement to permit passage of foreign products through the drier.The products being dried are fed from the feeder 13" through chute 14"between the cylinders 16" and 17, where they are pressed into a cakewhich passes down'between the large cylinder 15" and the small cylinders19" and 26'. During the travel of the products being dried they aresubject to contact with a hot drying gas admitted into the chamberthrough opening 12". The drying gases heat the cylinders and dry theproducts, then pass through the expansion chamber 21' from which theyare evacuated through conduit 23' by blower 22 and forced throughconduit 24' onto feed chute 14" of the feeder 13".

From the foregoing, it readily will be seen that there has been provideda novel process and improved apparatus for drying caking products;apparatus which comprises a drying chamber in which is mounted a pair offeed cylinders for receiving the products to be dried and form them intoa thin layer which passes onto a large central cylinder and rotatestherewith while being compressed by a plurality of laminating cylinders,and means for passing a flow of heating gas through said chamber to drysaid products; one in which all of the cylinders except the largecylinder, are mounted on movable axes to permit the passage through thedrier of any foreign objects in the products being dried.

While the hollow cylinders are heated both exteriorly and interiorly bythe hot gases passing through the chamber, obviously, they could beheated separately by other suitable means. Obviously, the exteriorsurface of the cylinders may be either smooth or corrugated.

Obviously, too, the invention is not restricted to the particularembodiments thereof herein shown and described.

What is claimed is:

l. A process of drying caking products such as mud or the like whichcomprises continuously feeding the products to be dried between a spacedpair of continuously rotating cylindrical surfaces rotating in oppositedirections in a chamber for pressing the products into a thin layer;continuously depositing the thin layer as formed onto a continuouslyrotating cylindrical surface rotating about a horizontal axis in saidchamber and continuously subjecting said layer of products as it rotateswith said last named surface to the laminating pressure of a pluralityof continuously rotating cylindrical surfaces whereby said layer will bemade thinner as it moves downwardly through said chamber; andcontinuously directing a flow of a hot gaseous medium downwardly throughsaid chamber for thoroughly drying said layer of products as it movesdownwardly through said chamber and so that the temperature of thedrying gas when it contacts the dried products will be reduced, therebyreducing the chance of spontaneous combustion when the dried productsare inflammable.

2. A process for drying caking products such as mud or the like, as setforth in claim 1, including the step of continuously withdrawing the hotgaseous medium from the bottom of the chamber and directing its flowagainst a surface wetted by the streams of wet products as they are fedinto the chamber, whereby any smaller particles in suspension in thegaseous medium will be precipitated and recovered with the driedproducts.

3. Apparatus for drying caking products such as mud or the likecomprising a chamber; means including a chute for feeding the productsto be dried into said chamber; a spaced-apart pair of feed cylindersrotatably mounted in said chamber for rotation in opposite directionsabout horizontal axes, said pair of feed cylinders being positioned toreceive between them the products discharged into the chamber by saidchute and press them into a thin layer as they pass downwardly betweenthe cylinders; a large cylinder mounted for rotation about a horizontalaxis and positioned in said chamber below said feed cylinders to receivesaid layer of products thereon as it is formed for rotation therewith; aplurality of vertically spaced laminating cylinders mounted in saidchamber for rotation about horizontal axes, said laminating cylindersbeing positioned to engage and press the layer of products passingbetween them and said large cylinder to make said layer thinner; andmeans including conduits for directing a flow of a hot gaseous mediumdownwardly through said chamber for drying said products as they movedownwardly therethrough and so that the finally dried products willcontact the drying gas after it has lost some of its heat, therebyreducing the chance of spontaneous combustion when said dried productsare inflammable.

4. Apparatus as set forth in claim 3, wherein means including conduitsand a blower are provided to suck the heated gaseous medium from thebottom of said chamber and blow it onto the wet products falling throughsaid inlet chute.

5. Apparatus as set forth in claim 3, wherein said large cylinder ismounted for rotation about a fixed axis and wherein all of the cylinderswhich engage the layer of products on said large cylinder are mountedfor rotation about axes movable toward and away from the periphery ofthe large cylinder, resilient means normally urging said movablecylinders toward said large cylinder, and adjustable thrust means forlimiting the pushing movement of said movable cylinders toward saidlarge cylinder.

6. Apparatus for drying caking products such as mud or the likecomprising a drying chamber; means including conduits for admitting aflow of a heated gaseous medium through said chamber; means including achute for feed ing the products to be dried into said chamber; a largecylinder mounted in said chamber below said chute with its shaftjournaled in fixed bearings for rotation about a horizontal axis; aspaced pair of feed cylinders mounted in said chamber between said chuteand the top of said large cylinder, each of said feed cylinders havingits shaft journaled in bearings slidably mounted in slide guideways;means including an adjustable thrust member and an adjustable springmember for normally holding one of said feed cylinders at apredetermined distance from the other of said feed cylinders; meansincluding an adjustable thrust member and an adjustable spring memherfor normally holding said other of said feed cylinders at apredetermined distance from the large cylinder; and a plurality ofvertically spaced laminating cylinders mounted in said chamber forrotation about horizontal axes and positioned to engage and compress thelayer of products on said large cylinder, the construction andarrangement being such that as the products being treated pass betweensaid feed cylinders they will be pressed into a thin layer and passedonto the large cylinder and be further compressed and thinned by thelaminating cylinders.

7. Apparatus as set forth in claim 6, wherein the upper of shaftlaminating cylinders has its shaft journaled in bearings carried by apair of levers pivotally suspended from the bearings of the other ofsaid feed cylinders and the remainder of the laminating cylinders havetheir shafts journaled in bearings carried by a pair of levers pivotallysuspended from the bearings of the preceding laminating cylinder.

8. Apparatus as set forth in claim 7, wherein each of said laminatingcylinders is movable toward and from said large cylinder to permit thepassage of foreign objects in the products being treated between thelarge cylinder and the laminating cylinders, and means, including anadjustable thrust member and an adjustable spring member, are providedfor normally holding said laminating cylinders a predetermined distancefrom said large cylinder.

References Cited in the file of this patent UNITED STATES PATENTS785,600 Ekenberg Mar. 21, 1905 1,530,439 Testrup et al. Mar. 17, 19252,068,181 Hurxthal Ian. 19, 1937 2,566,943 King Sept. 4, 1951 FOREIGNPATENTS 677,118 Germany June 19, 1938

